Injector flow test FAIL ?, Troubleshooting lean condition Options

[jim-c]

Im working on my recent 914 purchase. 2.0L engine. D-Jet ECU . Intially the engine would fire right up and idle smooth at 1000 rpm. Unfortunately it didn’t want to rev above idle. I could quick pump the throttle and get it to rev but it was undrivable.

I have an AFR gauge and it shows dead lean when i try to rev.
I did a flow test on two injectors ( all 4 are new ) . I have 28lbs of FP .
Full throttle and crank for 15 seconds yields 2cc per injector. Supposed to be 7 ish.

Any ideas ?

Nice new harness, MPS holds vacuum and has correct impedance readings.
The balance of sensors check out okay with test procedure. Fuel pump holds 28 lbs steady and pumped a quart of gas within 30 seconds .

[914sgofast2]

Low idle vacuum is likely a timing problem or undiscovered vacuum leak. Also, do you have the correct 123 Distributor that is set up to run with Djet? Not all the 123 Dizzys are compatible with Djet. You could be running on the cold start injector only if the 123 Dizzy is not sending the correct pulse signal to your ECU to fire the injectors.

Low fuel pressure could be a kinked rubber fuel line hose (or metal pipe) somewhere in the fuel system between the tank and the engine; or a faulty fuel pressure regulator that is stuck slightly open and sending a lot of the gas back to the tank.

Failure of fuel pump to run long enough is going to be a wiring (or internal ignition switch failure) or an ECU problem.

[emerygt350]

Low idle vacuum is likely a timing problem or undiscovered vacuum leak. Also, do you have the correct 123 Distributor that is set up to run with Djet? Not all the 123 Dizzys are compatible with Djet. You could be running on the cold start injector only if the 123 Dizzy is not sending the correct pulse signal to your ECU to fire the injectors.

Low fuel pressure could be a kinked rubber fuel line hose (or metal pipe) somewhere in the fuel system between the tank and the engine; or a faulty fuel pressure regulator that is stuck slightly open and sending a lot of the gas back to the tank.

Failure of fuel pump to run long enough is going to be a wiring (or internal ignition switch failure) or an ECU problem.

Very interesting! I didn't even consider the chance of a dizzy mismatch. I assume he was measuring pressure at the normal fitting so that should catch any of those issues I think. If the regulator was dumping it back to the tank the pressure at the nipple would drop. I know a good test would have to be under load (omg don't get me started with this crap on ford CFI systems) but even without load the engine has issues so if it were pressure problems, you would see it.

I really like your idea on the dizzy though. Easy to check.

Something else that might be interesting to try (and easy, perhaps you already mentioned trying it) would be jack your fuel pressure way up. I have had my regulator all the way up to 50 psi just to test out stuff (some dufus put a 1.7 injector in a 2.0). If nothing changes or barely changes, I would really start to pursue the computer/dizzy side. The injectors are not firing enough or long enough.